Method and device to create a foundation as well as a foundation

ABSTRACT

A method and a device to create a foundation in which a foundation pipe is driven into the soil. At least one bore is created into the soil in the perimeter area of the foundation pipe to insert before ramming by means of a drilling tool the diameter of which is significantly smaller than a diameter of the foundation pile. The soil material removed during drilling remains essentially within the bore. Furthermore, a foundation with a foundation pipe which is created accordingly.

The invention relates to a method for creating a foundation where a foundation pipe is driven into a soil.

Furthermore, the invention relates to a foundation with a foundation pipe being driven into the soil.

In addition, the invention relates to a device for creating a foundation with a foundation pipe in the soil and with a working platform with a ramming device to drive a foundation pipe into the soil.

A generic state of the art for inserting a foundation pipe in a seabed is known from DE 10 2011 111 036 A1. For the purpose of the foundation an offshore wind energy converter, a foundation pipe having a diameter of several meters is driven into a seabed with a ramming device from a floating pontoon. As ramming device the use of a vibrator is recommended. In order to reduce the required forces and noise emission, this publication teaches to guide a drilling tool on a drill rod through the ramming device to loosen the soil. In doing so, the drilling tool has a drill diameter which correlates approximately to the diameter of the foundation pipe to insert.

Drilling devices and drilling tools to create a bore with a diameter of several meters which can amount in the case of foundation pipes of wind energy converters up to 7 m and more, are very large, heavy and thus expensive. Such big and heavy devices can only be moved and adjusted with corresponding big handling devices, especially cranes. Moreover, during the drilling of large bore diameters under water an extensive clouding and therewith environment pollution of the surrounding water is created by drilling cuttings.

CH 622 305 A5 describes a method to insert steel piles into the soil with low noise emission. Here, the soil area in which a steel support is driven is loosened in advance by a bore. The diameter of the bore also corresponds approximately to the cross section size of the steel pile to be driven in.

The invention is based on the object to show a method and a device to create a foundation as well as a foundation, at which a foundation pipe also with large pipe diameter can be inserted efficiently as well as with a high load-bearing strength and stability in the soil.

The invention solves the object through a method, a foundation and respectively a device with the features having the features of the claimed invention.

The method according to the invention is characterized in that, before the impact driving by means of a drilling tool, which drill diameter is significantly smaller than a diameter of the foundation pipe, at least one borehole is produced in the soil in the perimeter area of the foundation pipe to insert and that soil material removed during the bore process remains to a large part in the borehole.

One basic idea of the method according to the invention is to loosen the soil through preceding drilling when impact driving a foundation pipe in the soil. However, braking up the soil is not done along the complete cross section of the foundation pipe to insert but only in the area of the perimeter wall of the foundation pipe. Thus the production of the bores can be carried out with conventional and therefor cost effective drilling devices and drilling tools. In addition, the bores can be produced with a relatively small diameter of preferably below 2 m, preferably between 20 cm and 80 cm. This kind of bore can be created with low noise as well as efficiently.

Furthermore, the method according to the invention offers a further advantage in that loosened soil material rarely accumulates and remains inside the foundation pipe. This positively influences load-bearing strength and stability of the foundation pipe in the soil.

On the whole, less soil material has to be bored up and removed. This both saves energy and is environmentally friendly.

According to a further development of the method according to the invention it is provided that several bores are created which are annularly arranged in the soil along the perimeter area of the foundation pipe to insert. Particularly the boreholes are inserted in an evenly spaced manner along the perimeter of the foundation pipe. Thereby, the foundation pipe has a diameter preferably of 2 m to 10 m or more. The boreholes can be created by traditional rotary drilling methods, in particularly with an auger, and preferably have a bore diameter between 0.2 m and 2 m.

According to a variant of the method of the invention a particularly good loosening can be achieved in that the bores are arranged in a touching or overlapping way. Thus the complete area along the foundation pipe is loosened by bores. Thus the pipe can be driven into the soil area with relatively low forces.

Alternatively, according to the invention it is provided that neighboring bores are created with a distance to each other, whereby a soil segment remains between neighboring bores. In the area of the remaining soil segments between the adjacent bores an increased wall friction can be achieved between the soil segment with the unchanged insitu soil and the wall of the foundation pipe. The distance of the bores to each other and thus the extent of the soil segments in the direction of the perimeter of the foundation pipe can be determined and adjusted depending on the soil strength.

According to a further development of the method according to the invention a further influence of the ramming forces and the bearing capacity of the foundation can be achieved in that at least one bore is sunk up to a drill depth which is less than or the same as the ramming depth of the foundation pipe. For example the one bore or the several bores can be sunk approximately only to the half of the intended ramming depth of the foundation pipe. In this way, the foundation pipe let itself insert into the soil with reduced forces in the first half, which facilitate a good guidance and alignment of the foundation pipe. Than the foundation pipe is inserted into the unchanged in situ soil in the second half of the driving-in so that in this half increased friction forces and thus a increased bearing capacity result.

Additionally, according to an embodiment of the invention it is preferred that the foundation pipe is driven into the soil by means of an impact driving device which is designed as a percussive driving hammer or an oscillating vibrator. Thereby, with a percussive driving hammer, especially a Diesel hammer, can apply great ramming forces in the form of percussive impulses. A more low noise inserting variant exist in that to drive the foundation pipe into the soil using an oscillating vibrator, in particular a vibration driver with rotating eccentric weights. Thus, ramming in the sense of the invention is a method in which essentially the foundation pipe is driven into soil through application of force without removal of soil material.

The method can in general be carried out onshore. An especially beneficial variant of the method according to the invention resides in that the foundation pipe is driven into the soil of a water body to form an underwater foundation. This method is especially advantageous for the foundation of offshore wind farms with foundation pipes having diameters of several meters. This type of foundations can not only be formed in a sea bed but also at a lake ground or in river ground.

According to another further development of the invention it is preferred that the drilling tool can be driven rotationally by a drilling device which can be adjusted on a work platform along the perimeter of the foundation pipe to insert. Here, the work platform can in particular be a pontoon or a so-called template which can be lowered to the ground of a body of water and can be adjusted thereon. If the platform is designed as a floating pontoon, the drilling device can be a traditional drill rig on a movable undercarriage. Therefore the drilling device can be moved automatically and can be moved to different drill positions at different locations of the work platform. Alternatively, the drilling tool can be driven by a so-called flying drilling device which is moved to the individual drilling positions by means of a rope suspension and a crane and there is fixed and adjusted to appropriate supports. Such a drilling device is also suitable for underwater drilling. Furthermore, the drilling device can be mounted on an adjustment device along the perimeter of the foundation pipe at the work platform such that the drilling device is able to move along a guideway by an actuator. Preferably, when sinking the device contacts the ground of the body of water with supports whereby the work platform remains over the water surface.

A preferable further development of the invention resides in that the work platform floats on the surface of the body of water or is lowered to the ground of the water body. Basically, the work platform can be both floatable and lowerable.

According to an embodiment variant of the invention it is advantageous that at least one circular drill guide is provided at the work platform which has guidance devices for the drilling tool according to the positions of the bores to introduce. The circular drill guide is a drill template which has a plurality of guidance devices for the axial guiding of the drilling tool at the desired positions. The guidance devices can especially be guide sleeves whose inner diameters are dimensioned adequately to the outer diameters of the drilling tools. Preferably, two drill guides are provided at the work platform, namely a first upper drill guide and a second lower drill guide. Preferably, the lower drill guide can be sunk from the work platform, particularly until it rests on the ground of the body of water. With this drill guide a particularly accurate deepening of the single bores can be carried out. Preferably the bores are arranged annularly such that the wall of the foundation pipe runs approximately through the center of the annularly arranged bores with the loosened soil material.

A preferred embodiment of the invention resides in the fact that during retraction of the drilling tool from the soil fill material, in particular a hardenable material, is fed to the borehole. During creating of the loosening bore a lowering can be formed after the retraction of the drilling tool. This lower leveling in the area of the bore has as a result that after the introduction of the foundation pipe into the loosened and partly lowered area the foundation pipe is not surrounded with soil up to the level of the ground of the body of water. Preferably fill material can be introduced into the bore via the drilling tool in order to not reduce the statistic useable embedding depth. Through this, a material or volume lost can be leveled out in the loosening bore. In the case of the fill material it can be every suitable material being pumpable, for example a free flowing solid, as sand, gypsum etc., or a mixing from solid, water and/or a hydraulic binder. During withdrawing of the drilling tool the fill material can be introduced via a centered liner pipe for compensating the material loss. Through the addition of a hardenable substance it even can be adjusted a selected stability of the loosened area.

The inserting of the fill material suitable for pumping can here be monitored preferably with regard to the amount per time or depth or also with regard to the in-situ pressure. Thereby it is assumed as enough that the pressure in-situ below on the output opening approximately corresponds to the hydrostatic pressure which is present in the liner pipe as a result of the liquid stand. If desired the pressure can be increased also in the particular case.

The foundation according to the invention is characterized in that at least one bore is inserted into the soil in the perimeter area of the foundation pipe before the impact driving process, the bore diameter of which is considerably smaller than one diameter of the foundation pipe and that the at least one bore is filled with soil material which accumulates while producing the bore. The diameter of the bore is thereby bigger than the wall of the foundation pipe and normally amounts to between 5% and 30% of the diameter of the pipe to insert.

With the foundation according to the invention results the above described advantages with regard to the more efficient and more cost-efficient producing as well the bearing capacity.

According to the invention the device to create a foundation is characterized in that a drill device with drilling tool is provided at the work platform whose drill diameter is significantly smaller than a diameter of the foundation pipe to insert and that the drilling device can be adjusted along the perimeter area of the foundation pipe to drive in. With this device according to the invention especially the method according to the invention described above can be carried out. The advantages described above are achieved hereby.

A preferred embodiment according to the invention results in that the work platform is designed floatable and/or can be lowered for forming an underwater foundation. Thus, the device can be used particularly for maritime application purposes, particularly to create a foundation for offshore wind power plants or other offshore applications.

According to a further embodiment of the invention it is advantageous that the drilling device has a pipe-shaped drilling tool via which pipe interior fill material can be introduced into the bore. Particularly, the fill material can be pumped into the bore by means of a pump device. With the fill material a material or volume loss can be compensated, which can arise during creating the loosening bore. By introducing a hardenable fill material the stability can be adjusted in the area of the loosening bore and all in all anchorage of the foundation pipe can further be improved.

Subsequent the invention is further described by preferred exemplary embodiments which are depicted schematically in the drawings. The drawings show in:

FIG. 1 a schematic perspective view of a device according to the invention when constructing a foundation according to the invention; and

FIG. 2 a schematic top view of an inserted foundation pipe according to the invention.

According to FIG. 1 the creating of a foundation in the soil 3 of a body of water 4 is depicted. A device 10 according to the invention with a floatable work platform 12 is initially positioned at the desired position on a surface 6 of the body of water 4. Then four supports 18 are lowered in a basically well-known way at the work platform 12, wherein the supports 18 are anchored in the soil 3 of the body of water 4. Then the work platform 12 can be lifted. The device 10 is used to insert a foundation pipe 1 which can especially be used as a foundation for an offshore wind energy converter. Such foundation pipes 1 have a diameter of several meters, particularly between 5 meter and 10 meter.

Before the foundation pipe 1 is forced or driven into the soil 3 the soil 3 is loosened circularly in the area of the wall of the foundation pipe 1 by rotary inserting of bores 5. The bores 5 are thereby produced by a drill device 20 through which at the desired positions a drilling tool 22, preferably designed as an auger, is inserted into the soil 3.

In the depicted exemplary embodiment the drilling device 20 is a traditional mobile drilling rig with a movable undercarriage and an adjustable, especially rotatable upper carriage with mast arranged thereon, along which a drill drive is mounted in a vertically adjustable manner for rotary driving the drilling tool 22. The drilling device 20 can be moved along a flat work surface 13 on the work platform 12 to desired working positions. On the flat work surface 13 a further movable accessory device 40 is shown. This can be used to handle the foundation pipe 1 or the drilling tool 22. Alternatively, as accessory device 40 also a further drilling device can be provided so that basically the drilling work can be carried out twice as fast.

For an accurate sinking the bores 5, which are schematically shown in FIG. 2, an upper drilling guide 14 to guide the drilling tool 22 is arranged in the upper area along a vertical work transit at the work platform 12. The drill guides 14, 15 are preferably designed as circular drill templates. Within this upper drill guide 14 the ramming device 30, only schematically indicated, can be arranged for driving-in the foundation pipe 1. For an especially exact guiding a lower drill guide 15 with tubular guide mechanisms 16 is arranged. The circular lower drill guide 15 can be sunk from the work platform 12 up to the ground of the body of water 4 by means of hoist ropes 17.

Alternatively, the ramming device 30 can also be positioned on a separate second working platform. In this case, the first working platform 12 with the drilling device 20 is removed after having created the borings 5 and is replaced by the second working platform with the foundation pipe 1 and the ramming device 30. After a corresponding positioning, the foundation pipe 1 is then driven into the soil 3 in the area of the bores 5.

In this way, a plurality of bores 5 can be provided circularly along a perimeter of the foundation pipe 1 to drive in for loosening the soil 3. The circular arrangement of the bores 5 is shown schematically in FIG. 2. According to the shown exemplary embodiment eight bores 5 are sunk into the soil 3. The bores 5 are positioned circularly along the perimeter of the foundation pipe 1 to insert so that a wall of the foundation pipe 1 runs in each case approximately centrically through the bores 5. The bores 5 are created in such a way that the soil material removed during drilling remains essentially in the bore 5. Through the bores 5 a distinct loosening of the soil 3 is achieved, in particular in the case of hard soil. This allows successively the foundation pipe 1 to force or to drive into the soil 3 with lesser forces.

In general the bores 5 can be created in a touching or overlapping manner in a circular arrangement. In the shown exemplary embodiment according to FIG. 2, the bores 5 are designed in a mutually spaced manner wherein one soil segment 7 with not loosened up soil material remains between the bores 5 with loosened up soil material. 

1.-15. (canceled)
 16. Method to create a foundation in which a foundation pipe is driven into a soil, wherein that before the driving-in by means of a drilling tool the diameter of which is significantly smaller than a diameter of the foundation pipe at least one bore is created into the soil in the perimeter area of the foundation pipe to insert, and that the soil material removed during drilling remains essentially in the bore.
 17. Method according to claim 16, wherein that several bores are created which are arranged circularly in the soil along the perimeter area of the foundation pipe to insert.
 18. Method according to claim 17, wherein that the bores are arranged in a touching or overlapping manner.
 19. Method according to claim 17, wherein that adjacent bores are created with a distance to each other whereby a soil segment remains between the adjacent bores.
 20. Method according to claim 16, wherein that the at least one bore is deepened up to a drill depth which is less than or is the same as the ramming depth of the foundation pipe.
 21. Method according to claim 16, wherein that the foundation pipe is driven into the soil by means of a ramming device which is designed either as percussive drive hammer or an oscillating vibrator.
 22. Method according to claim 16, wherein that the foundation pipe is driven into the soil of a body of water to create an underwater foundation.
 23. Method according to claim 22, wherein that the drilling tool is driven rotationally by a drilling device which can be moved on the working platform along the perimeter of the foundation pipe to insert.
 24. Method according claim 23, wherein that the work platform floats on the surface of the body of water or is lowered to the ground of the body of water.
 25. Method according to claim 23, wherein that at the work platform is provided at least one circular drill guide which has guidance devices for the drilling tool according to the positions of the bores to insert.
 26. Method according to claim 16, wherein that during the drawing back of the drilling tool from the soil fill material, in particular a hardenable material, is fed to the bore.
 27. Foundation with a foundation pipe which is driven into a soil, in particularly according to a method according to claim 16, wherein that at least one bore is inserted into the soil in the perimeter area of the foundation pipe before the driving-in, the bore diameter of which is significantly smaller than a diameter of the foundation pipe and that the at least one bore is filled with soil material which accumulates during creating the bore.
 28. Device to create a foundation with a foundation pipe into the soil, in particularly to carry out a method according to claim 16 with a working platform including a ramming device to drive the foundation pipe into the soil, wherein that on the work platform is provided a drilling device with drilling tool, the drill diameter of which is significantly smaller than a diameter of the foundation pipe to install, and that the drilling device can be moved along a perimeter area of the foundation pipe to drive in.
 29. Device according to claim 28, wherein that the working platform to create an underwater foundation is designed floatable and/or lowerable.
 30. Device according to claim 28, wherein that the drill device has a pipe-shaped drilling tool via which pipe interior fill material can be introduced into the bore. 